1. Field of the Invention
The invention relates in general to illuminating instrument cluster display components and more specifically to providing different-colored backlighting to separate segments of an instrument dial face.
2. Discussion of Related Art
The stylish appearance of instrument cluster displays in the instrument panels and dashboards of vehicles has become very important to the final customer, and therefore the vehicle maker. The multiple color requirements are highly challenging to achieve using light emitting diodes. The problem has been temporarily addressed by using incandescent bulbs as the backlighting source for instrument dials. However, incandescent bulbs have shorter life spans than light emitting diodes, raising issues such as reliability and bulb replacement costs. Optional arrangements that enable the efficient use of light emitting diodes to get the multi-color light effect would have important advantages. Instrument clusters require multiple dials and displays and they all need to be illuminated, so part count and material weight become important issues.
Light emitting diodes require much less power than incandescent bulbs, but are not as bright or intense. To reduce the need for large numbers of light emitting diodes to light a single dial face, reflectors, such as the one disclosed in U.S. Pat. No. 6,508,562, are often designed to evenly spread light over the area of the dial using as few light emitting diodes as possible, while providing the necessary illumination intensity. Typically, as suggested by an embodiment disclosed in U.S. Pat. No. 6,595,667, same-color diodes are used to illuminate an entire display face including background field, scale, characters and pointer. This fails to provide a distinctive appearance. In another embodiment of the same patent, when the colors of illumination from the light sources are chosen to be different, they are completely separated by partitions to prevent the light sources from interfering with each other. This could require larger numbers of light emitting diodes to get the lighting correct and greater material needs for more complex reflectors, increasing the number of parts, weight and cost.